In Direct Imaging (DI) systems, a scanning beam is used to directly write an image, one or more pixels at a time, onto an exposure surface such as a photoresist. In systems that are known in the art, the image is typically created by modulating a scanning beam based on stored image data. The modulated beam is scanned in a raster pattern as the exposure surface (or scanning beam) advances in a scan direction.
Some DI systems use multiple beams in parallel to increase writing speed. For example, U.S. Pat. No. 7,046,266 describes a method of scanning for writing a pattern on a surface, including providing a scanning beam comprising a plurality of independently addressable sub-beams, which scan the surface side-by-side in the cross-scan direction. Each sub-beam is modulated to reflect information to be written, and the beams are overlapped in successive scans in the cross-scan direction such that all written areas of the surface are written on during at least two scans.